Problems with Telecom's JetStream ADSL network seem to have spread from the new - and so far unsuccessfully installed - equipment to software in an existing switch.
On September 29 DSL subscribers south of Taupo lost service for two hours, due to a switch failure in the network.
Telecom has made at least two unsuccessful attempts in the past month to install a Siemens ERX remote access switch to replace a Nokia Redback switch in the DSL network at the Wellington node. Both times, the network collapsed and denied service to customers south of Taupo.
A week ago the same customers were affected, but this time by a failure in the existing Redback switch. "The [latest] problem was caused by a software bug," says a Telecom spokeswoman. "We believe we now know how it was triggered."
Meanwhile, the Siemens ERX is still not ready for another attempt at installation, Telecom says. The problem arose with users entering erroneous passwords and leaving them in the network uncorrected. Telecom's Nokia modems kept retrying the false passwords and congested the remote access switch. This was really a problem with Telecom's testing suite for the switch before attempted installation.
"We try to reproduce all possible user behaviour in our testing environment; but people are unpredictable, and we didn't foresee them doing what they did."
The testing environment is now being amended and when this is done, tests will be repeated. If the ERX passes these, another attempt will be made to reinstall it.
The new switch is intended to cope with traffic growth, having 10 times the capacity of the Redback, says Telecom. If capacity problems develop in the interim "we have options to cope with it, like rerouting through Auckland".